Woolite is a pretty good, mild detergent for seat cleaning. I've used it with good results on both leather and fabric. Dilute ~ 5:1 for mild cleaning and 10:1 for heavy duty cleaning. For leather it is easy to wipe it clean with a towel, but for cloth I'd do the same as what Martin suggests - a heavy duty shop vac to suck as much water out as possible and then let it sit outside in the sun to finish it off.